Measure of Tendency 5 - Sample Question 3: Using Group Frequency Table

Question:

Here is the table that show the duration of time and frequency. How to find Mean of the grouped data? 

 

Answer:

We can estimate the Mean by using the midpoints.

Let's now make the table using midpoints:

Next, we add up the frequencies in order to get the total number of frequency. Then, we need to multiply each midpoint by each frequency and adding them up to get the total (= 619).

Lastly, we divide the total by 20 in order to get the estimated number of mean.